Molded carton construction



NOV. 26, 1946. R U E ETAL I 2,411,622

' MOLD ED CARTON CONSTRUCTION Filed oct. 4, 1945 @wmfam Patented Nov. 26, 1946 MOLDED CARTON CONSTRUCTION Reynolds Guyer and Robert M. Dunning, St. Paul, Minn., assignors to Waldorf Paper Products Company, St. Paul, Minn., a corporation of Minnesota Application October 4, 1943, Serial No. 504,820-

. 7 Claims. 1

Our invention relates to an improvement; in carton construction wherein it is desired to provide a novel type of sift-proof carton having molded corners thereupon.

The recent application of Reynolds Guyer, Serial No. 485,726, described a carton construction in which the corners of the cartons were molded, preferably by pressure, heat, or both so that any small aperture in a corner of the carton will be sealed. In this application the corners of the carton and any or all of the external seams thereof could be molded so as to change the form of the stock of which the cartons were formed atcertai points thereof. In the preferred embodiments of the former invention the corners of the carton were either moistened before being molded with pressure or with combined pressure and heat to liberate the fibers of the carton stock to some extent, or else the carton was coated with a coating of suitable material such as wax and this wax was caused to impregnate into the material of which the carton was formed in the molded areas.

We have found that if the cartons are formed of certain types of material, the molding operation has a tendency to set the stock in molded formation without the necessity of a separate coating. For example if the carton is formed of two sheets of paper laminated with a laminating agent which softens upon application of heat and pressure, the carton corners may be molded to their proper shape with a heated die or the like and held in molded position until set. The laminating material softens during the molding process and then sets in molded form, holding the box corners in molded'shape.

A feature of the present invention lie in the provision of a carton formed with a normally in- .active substance therein; such as a laminating material, an ingredient'formed directly in the paper, or a normally inactive coating on the material, which when heated softens to permit the stock of which the carton is formed to be molded into the desired configuration. Upon rehardening after the molding process, the carton corners remain in molded shape and therefore the gradual return of the carton to its original shape and the consequent reappearance of minute apertures therein i prevented.

A further feature of the present invention lies in coating, impregnating, or embodying in at least selective portions of the carton stock a material which tends to soften upon application of heat sufficiently to seal the interstices in the carton,

and which upon cooling will stiffen sufllcientlycation:

to retard or prevent the natural tendency for the carton stock to return to its normal position. As a result selected portions of the carton, such as the corners thereof, are stiffened and sealed, thereby sealing any aperture which previously occurred at the .corner and also protecting the corners of the cartons so molded from developing any apertures. As a result the carton is effectively sealed and tends to remain sealed even when carelessly handled.

These and other objects and novel features of our invention will be more clearly and fully set forth in the following specification and claims.

In the drawing forming a part of our-specifi- Figure 1 is a, perspective view of a typical carton before the molding operation.

Figure 2 is a perspective view of the same carton after the molding operation. 3

Figure 3 illustrates a section of paper of which the carton may be formed, showing a laminated construction thereof. Figure 4 is a diagrammatic view of a typical carton blank and showing a coating of thermoplastic material applied locally at the areas most likely to develop sifting.

Figure 5 is a view similar to Figure 4 illustrating another manner of applying thermoplastic material locally to a typical carton blank.

Figure 6 is another diagrammatic view similar to Figures 4 and 5showing still another manner of applying thermoplastic material to a typical carton blank. 'I'he carton ,A illustrated in Figures 1 and 2 of the drawing may be of any desired shape or form. The carton illustrated comprises rectangularly arranged side and end wall such as l0 and II, and top and-bottom walls such as l2. Before the molding operations square corners are provided between the various walls of the carton. After the molding operation, however, the corners are forme inwardly and somewhat rounded in the manner indicated in Figure 2 of the drawing, the rounded corners beingdesignated by the .numeral l3. p

The molding of the carton can be accomplished by various methods, such as by applying a heated die to opposite end of the carton so as to mold the corners thereof.

We have found that if the carton is laminated and formed of two or more thicknesses of material, such as is indicated by the numerals i4 and IS in Figure 3 of the'drawing, and if the laminating material I6 is of the type to soften upon application of heat, the carton comers may completion of ing the cooling process,

formation and resist the return of the 1 means of a glue flap 22.

atlases I be made to retain their molded condition at the the molding operation. For example, if asphalt is used as the mating agent I6, by heating the mold sufficiently to soften the asphalt during the molding operation and by holding the molded corners in molded form durthe asphalt will harden in molded carton stock to its original position.

Materials such as thermoplastic resins have also been used for this purpose with excellent results. Such thermoplastic resins must be selected so as not to injure or 'afiect the material being packaged. Rosin bearing resins have been used with good results for the purpose, although such materials are preferably used in locally coating selected portions of the carton.

Normally dry adhesives with good success in laminating or coating. selected areas of the carton stock. Certain such adhesives which have been used include mixtures of resin, rubber and size, which are normally elastic, but which include sufllcient resin to prevent the molded carton corners from returning to their normal state. Such materials have a tendency to impregnate into the carton stock upon application of heat and be spread through the stock, facilitating the maintenance of the rounded comer construction.

In Figure 4 of the drawing we disclose a typical carton blank formed of a series of side wall panels l1, I9, 20 and 2|, foldably connected along parallel fold lines and connected together by These panels are connected along substantially aligned fold lines 23 and '26 to end flaps 25, 26, 21 and 29. These end flaps are designed to fold together to form a carton closure at each end of the carton, as is common practice.

In the formation of the carton a band of thermoplastic material 80 is coated along the fold line 28 to extend on opposite sides thereof. A similar band Si is coated along the fold line 24v to extend on either side of the fold. Thus the thermoplastic material is provided encircling the carton where the various end flaps are connected to form a closure. As occur at the corners of the carton the thermoplastic material is thus coated adjacent the corners.

It will be noted that upon application of heat and pressure to the corners of the carton blank illustrated in Figure 4, the thermoplastic material adiacent the corners of the carton and adjacent the seams thereof caused to impregnate into the carton stock, filling any interstices between the various flaps and panels at the corners of the carton. Thus the corners will be effectively sealed and the carton rendered sift-proof.

In Figure 5 of the drawing we disclose a blank similar to that illustrated in Figure 4 of the drawing, and including wall panels 32, 33, II, and 35 connected by fold lines and adapted to be connected together by means of glue flaps 36. These panels are connected along a fold line 31 to end closure flaps 39, along the fold line 43 to similar end closure flaps 39, Mi, M, and 32.

In order to seal the carton areas it of thermoplastic material, they are'provided adjacent the inner section of the fold lines 3i and 63 with the vertical fold lines separating the various panels forming the carton walls. After the carton has been folded into the form illustrated in Figure 1 apertures most frequently will be heated and have also been used 2 els being connected together by a glue of the drawing and molded into the mm illus= trated in'Figure 2 of the drawing, the area dd closure. In this construction themarginal edges of each of the flaps 53, 54, 56, and 56 are coated with a strip of thermoplastic material 51, which -extends somewhat beyond the fold lines BI and 52 soas to completely encircle the corners of the carton after the same has been folded. Upon application of heat and pressure to the ends of the carton, the thermoplastic material 51 will soften and fill any interstices through the car- 1 ton, completely sealing the edges of the various all of 60, ll, and i2, and are connected composing the panels flaps together. If a cement is used for sealing the flaps, which is sensitive to heat, the entire ends of the carton may be heated, only the coated portions thereof being affected by this heat.

It will be noted that the foregoing construc- 7 tion holds the molded corners of the carton in molded formation, acts to fill the carton comers, and acts to prevent the corners from breaking open or sifting during transportation or handling thereof. If it is desired the thermoplastic material may be added directly to the carton stock in place of using the same as a laminating agent, or in place of coating the same on selected portions of the carton blank, each of these constructions having individual advantages and disadvantages over the other forms of construction.

In accordance with the patent statutes, we have described the principles of construction and operation of our carton construction and while we have endeavored to set forth the best embodlment thereof, we desire to have it understood that obvious changes may be made within the scope of the following claims without departing from the spirit of our invention.

We claim:

l. A sealed package comprising a series of panels connected together to completely enclose the packag contents, the material composing the panels including at least in the area of the trihedral corners at one end of the carton a thermoplastic material, each said trihedral corner having its apex compressed in predetermined beveled or rounded form,.said thermoplastic material operating to hold said corners permanently in said predetermined form.

2. A sealed package comprising a tubular carton formed of a series of connected wall panels.

and end panels closing the ends thereof to completely enclose the carton contents, the material including at least in the area of the trlhedral corners between the panels and end walls at one end of the carton a thermoplastic material, each said trihedral corner having its apex compressed in predetermined beveled or rounded form, saidthermoplastic material operating to hold said corners permanently in said predetermined form.

3. A sealed package comprising a carton having rectangularly arranged carton wall panels connected together and end panels connecting the ends'of said wall panels to completely enclose the carton contents, the material composing the panels including at least in the area of the trihedral corners at one end of the carton a thermoplastic material, each said trihedral corner having its apex compressed in predetermined beveled or rounded form, said thermoplastic material operating to hold said corners permanently in said predetermined form. I

4. A sealed package comprising a series of panels connected together to completely enclose the package contents, the material composing the panels comprising sheets of cellulosic material laminated together with a thermoplastic adhesive, each trihedral corner at at least one end of the carton having its apex compressed in predetermined beveled or rounded form, said thermoplastic adh s e'oper t g to hold said-corners permanently in said predetermined form.

5. A sealed package comprising a tubular carton formed of a series of connected wall panels, and end panels closing the ends thereof to completely enclose the carton contents, the material composing the panels comprising sheets of cellulosic material laminated together with a thermoplastic adhesive, each trihedral corner at at least one end of the carton having its apex compressed in predetermined beveled or. rounded form, said thermoplastic adhesive operating to mined form.

hold said corners permanently in said predetermined form.

6. A sealed package comprising a carton having rectangularly arranged carton wall panels connected together and end panels connecting the ends of said wall panels to completely enclose the carton contents, the material composing the panels comprising sheets of cellulosic material laminated together with a thermoplastic adhesive, each trihedral corner at at least one end 01 the carton having its apex compressed in predetermined beveled or rounded form, said thermoplastic adhesive operating to hold said corners permanently in said predetermined form.

'7. A sealed package comprising a series of panels connected together to form a substantially rectangular carton to completely enclose the package contents, the material composing the panels including at least in the area of the trihedral corners of the carton a thermoplastic material, each trihedral cornerhaving its apex compressed in predetermined beveled or rounded form, said thermoplastic material operating. to hold said corners permanently in said predeter- REYNOLDS GUYER. ROBERT M. DUNNING. 

